The IBM System z9e introduces the enhanced book availability (EBA) feature to reduce the number of planned system outages. Included as part of the EBA feature is the concurrent book replacement (CBR) function, which allows a single book in a multibook server to be concurrently removed from the system in order for service personnel to perform a repair or to physically upgrade the hardware on the book. This repaired or upgraded book is then concurrently replaced and reintegrated into the server configuration. In this paper, we describe the benefits that the concurrent book replacement function offers a customer during a planned repair or upgrade of the System z9. We also describe a tool, developed to analyze the server in order to determine whether the server is ''prepared'' for the concurrent book replacement operation, and we provide an overview of the actions performed by this tool. The paper also contains a description of the concurrent book replacement operation, with an emphasis on the unique functions developed as part of this design.